Prostate cancer-specific survival differences in patients treated by radical prostatectomy versus curative radiotherapy

Abstract

Objective: We compared the cause-specific survival of patientswho received radiotherapy to those who received surgery for cureof their prostate cancer using a number of design and analytic stepsto mitigate confounding by indication.Methods: This was a case-cohort study of 2213 patients in theOntario Cancer Registry diagnosed between 1990 and 1998 whowere either treatment candidates or received curative radiotherapyor surgery. Cases included patients who died of prostate cancerwithin 10 years. The study population was restricted to those whowere candidates for either treatment (radiotherapy or surgery)based on disease severity (low and intermediate risk using theGenitourinary Radiation Oncologists of Canada risk groups). Themedian follow-up was 51 months. Cause-specific survival wasanalyzed using Cox-proportional hazards regression with casecohortvariance adjustment.Results from intent-to-treat analyseswere compared to results by treatment received.Results: Adjusted hazard ratios for risk of prostate cancer death forradiotherapy compared to surgery for the entire study populationwere 1.62 (95%CI 1.00-2.61) and 2.02 (1.19-3.43) analyzing byintent-to-treat and treatment received, respectively. Intent-to-treathazard ratios for the low- and intermediate-risk groups were 0.87(0.28-2.76) and 1.57 (0.95-2.61), respectively.Conclusion: Overall results were driven by the finding in the intermediate-risk group, which indicated that radiotherapy was not aseffective as surgery in this group. Confirmation was needed withspecial attention paid to risk stratification and the impact of morecontemporary delivery of these treatment options.